1. Field of the Invention
The invention relates to an assemblage for the introduction of a catheter into a vein while protecting the clinician from accidental needle sticks after withdrawal of a sharp needle. The assemblage may be used for regular over the needle catheters made of a stiff material, or with slight modifications, for introducing a long soft catheter thru a peelable introducer sheath.
2. Background of the Invention
A body penetrating needle is probably the most highly used instrument employed by physicians and nurses. The penetration of the body tissue is generally accomplished by a sharpened end of a hollow needle, which normally is inserted through subcutaneous body tissue to penetrate a selected vein lying close to the body surface. Thousands of such needles are employed daily for the injection of medicinal fluids, by having the non-inserted end of the needle connected to a hypodermic syringe. In many cases, however, a continuous controlled flow of fluid into the selected patient vein is desired and the sharpened hollow needle is employed to penetrate the selected vein and effect the introduction of a catheter into such vein. The catheter is in turn connected to an elevated bag of medicinal fluid after the hollow needle is withdrawn from the body and the catheter.
In other cases, it becomes highly desirable to inject the medicine at a vein location closer to the central vasculature for better hemodilution. In such case, a sharpened hollow needle is employed to effect the initial puncture of the selected vein. An axially splittable catheter sheath or introducer is mounted in surrounding relationship to the body of the needle and follows the needle into the selected patient vein. The needle is then withdrawn from the catheter introducer, and a small diameter, flexible catheter is fed through the bore of the catheter introducer into the vein, and then along the vein to a position to which direct application of medication is desired. The catheter sheath is then withdrawn and axially split for removal from the body and the catheter. See, for example, U.S. Pat. No. 4,306,562 to Osborne.
In all such utilization of hollow needles having sharpened ends, there is always the risk that the physician or nurse using the needle may be scratched by the sharpened end of the needle following its withdrawal from the patient's body. The same risk of inadvertent scratching is faced by those medical health personnel who have to dispose of the used needles. The prevention of accidental scratching of any person by a used needle is obviously highly desirable to minimize accidental infection from patients who have HTLV (AIDS) virus, hepatitis or other highly infectious diseases. There is also the risk of inadvertent contact with blood leaking out of the end of the needle when withdrawn from the body.
The problem of safe, yet convenient placement of catheters in a patient's vein or other body organ has been recognized in the prior art. U.S. Pat. No. 4,832,696 to Luther, et al. provides a needle assembly comprising an elongate hollow housing which mounts the needle. A needle guard is slidably mounted within the housing and is adapted to be moved forward along the needle. Following use, the needle and housing are retracted and the needle guard becomes permanently locked with the housing in a position in which it covers the needle.
A similar device is disclosed in U.S. Pat. No. 4,950,252 to Luther, et al. In both of the aforementioned Luther, et al. patents, the needle assembly is primarily designed to permit the insertion of a so-called "over-the-needle" catheter. In other words, a short length, relatively rigid catheter is mounted in surrounding relationship to the hollow needle whose sharpened end projects out of the end of the catheter. The catheter is then inserted into the selected patient vein concurrently with the penetration of the vein by the sharpened end of the hollow needle. When the needle is withdrawn, the catheter remains in position and may be secured to the patient by adhesive tape so that it may be repeatedly used.
Unfortunately, catheters of the type for which the Luther, et al. needles were designed can only be permitted to remain in the patient for a period generally not in excess of 48 to 72 hours. This limitation is probably due to the relatively stiff material the catheter is made of which is required for the over-the-needle catheter in order to permit the sealed attachment thereto of a tube leading to a bag of medicinal fluid.
Another requirement of a catheter placement apparatus is that after the needle and catheter have been presumably inserted into a vein (venipuncture), the proper insertion must be confirmed by a flow of blood from the vein. Hence, it is highly desirable that the needle mounting assemblage include a flash chamber having at least a portion of its walls transparent and being in communication with the outer end of the hollow needle so that the initial flow of blood may be readily observed by the operator of the needle. This problem is discussed in U.S. Pat. No. 4,108,175 to Orton, who also discusses at length the desirability of having a needle operating mechanism that can be controlled entirely by one hand.
U.S. Pat. No. 4,160,450 to Doherty discloses a protective mounting assemblage for a venipuncture needle wherein the needle is secured to a hub which is slidably mounted within a hollow housing. The movements of the needle relative to the housing are produced by movements of a tube projecting axially out of the housing. After venipuncture has been achieved, the tube is pulled outwardly relative to the housing to retract the needle within the housing. This structure obviously cannot be employed for insertion of an elongated catheter into the selected vein. Medication must be supplied through the tubing that is operatively connected to the hub mounting the needle.
U.S. Pat. No. 4,676,783 to Jagger, et al. discloses a needle protective apparatus similar to the Doherty patent.
U.S. Pat. No. 4,664,653 to Sagstetter, et al. discloses a hypodermic syringe wherein the same needle may be repeatedly utilized, a feature contraindicated in clinical IV protocols. The needle is pushed forward relative to a housing by a plunger element to penetrate a bellows-type covering element and move into puncturing engagement with the skin of the patient. Following the injection of medication, pulling back the plunger will retract the needle into the interior of the bellows unit which assumes an axially extended cylindrical configuration. Obviously, this construction provides no help in reducing the transmission of infectious diseases by repeated usage of a needle.
U.S. Pat. No. 4,702,738 to Spencer discloses a hypodermic syringe wherein the needle is moved between an operative and an inoperative protected position by axial movement of a plunger mounting the needle relative to a surrounding housing. This structure could not be effectively employed for the insertion of a short catheter or a catheter introducer into the patient's vein.
U.S. Pat. No. 4,747,831 to Kulli discloses a needle operating assemblage which can be utilized for insertion of a cannula or over-the-needle catheter wherein the positioning of the needle in its operative opposition compresses a spring between a shoulder provided on the outer end of the needle and a latch mounted for radial movement relative to the housing. After the venipuncture is accomplished, depressing the latch permits the needle to be retracted by the spring to a position where in the pointed end of the needle lies within the end of the housing.
U.S. Pat. No. 4,664,654 to Strauss also utilizes a compressed spring to return the needle to its protected position within the housing.
U.S. Pat. No. 3,536,073 to Farb discloses an enlarged needle having a bore of sufficient diameter to accommodate a catheter. The needle is secured to a plunger which is slidably mounted within housing. A tubular protective sheath is disposed intermediate the needle and the housing and the protective tubing can be advanced to surround the needle after it is withdrawn from the patient's body. This structure obviously requires that the entire operating apparatus be slidably removed over the entire length of the catheter.
U.S. Pat. No. 3,463,152 to Sorenson discloses a catheter placement unit for inserting a catheter into a patient vein through the lumen or bore of the hollow needle. Once the catheter placement has been made, the needle is retracted and is secured in a retracted position in a housing by a strip of adhesive tape which holds the entire apparatus on the patient's body. This is obviously a highly undesirable feature.
Lastly, U.S. Pat. No. 4,781,692 to Jagger, et al. discloses a protective arrangement for a catheter insertion needle wherein the needle is pulled into a protective position within a surrounding tube by a pulling force applied through a flexible tube.
The foregoing discussion of the prior art indicates that many efforts have been made to provide a simple, economical, yet highly protective mechanism for inserting a catheter of either the short, rigid type or the long, flexible type into a desired location in a patient's vein, nonetheless, there is room for improvement of such devices and such improvements are provided by the present invention.